Interpretive Summary: Various agricultural residues such as corn fiber, corn cob, wheat and rice straws contain complex structures which are difficult to breakdown. We recently found that a yeast-like fungus produces a novel highly thermostable enzyme that has the ability to breakdown these complex components to simple sugars. We undertook this research to optimize production of this novel thermostable enzyme. We found that the simple sugar arabinose was most effective for the production of the enzyme. The results will serve as a basis to design appropriate strategies for production of the enzyme. The enzyme has potential for use in the production of fermentable sugars from various hemicellulosic agricultural residues and to improve animal feed digestibility by hydrolyzing a major component of animal feed.

Technical Abstract:
A color-variant strain of Aureobasidium pullulans (NRRL Y-12974) produced alpha-L-arabinofuranosidase (alpha-L-AFase) when grown in liquid culture on sugar beet arabinan, wheat arabinoxylan, L-arabinose, L-arabitol, xylose, xylitol, oat spelt xylan or corn fiber. L-arabinose was most effective for production of both whole-broth and extracellular alpha-L-AFase activity, followed by L-arabitol. Oat spelt xylan, sugar beet arabinan and wheat arabinoxylan were intermediate in their ability to support alpha-L-AFase production. Lower amounts of enzyme activity were detected in corn fiber- and arabinogalactan-grown cultures.